| Jodie & DAN 3D Ltd | Health & social care | 2019 |
| Jodp Limited | Health & social care | 2014 |
| JOE Barlow Ltd | Information & communication | 2015 |
| JOE Drury Plumbing and Heating Limited | Construction | 2013 |
| Joemab Trading Ltd | Wholesale & retail | 2020 |
| JOG Transport Limited | Transport & logistics | 2025 |
| John Allen Management (UK) Ltd | Information & communication | 2023 |
| John Cade Limited | Wholesale & retail | 1975 |
| John Crane Limited | Extraterritorial | 1984 |
| John Edgerton & Co Limited | Real estate | 2003 |
| John Harris Associates Ltd | Professional & scientific | 2018 |
| John Harris Homes Ltd | Real estate | 2022 |
| John Lynch Consultancy & Training Ltd | Professional & scientific | 2014 |
| John Percy Plumbing and Heating Ltd | Construction | 2020 |
| John Ritchie Farms Limited | Agriculture & fishing | 2012 |
| John Scofield Photography Limited | Professional & scientific | 2022 |
| Johnny Locum Services Ltd | Professional & scientific | 2024 |
| Johnston Accountancy Limited | Professional & scientific | 2022 |
| JOHNY27 Ltd | Transport & logistics | 2017 |
| Joint Leisure Purchasing Limited | Wholesale & retail | 1989 |
| Joint to Joint Ltd | Construction | 2026 |
| Jollof After Dark Limited | Hospitality | 2025 |
| JON Hair Fashions Limited | Other services | 2002 |
| Jonach Limited | Information & communication | 2011 |
| Jonathon Brown Dentistry Ltd | Financial services | 2018 |
| Jones Dental Associates Ltd | Health & social care | 2024 |
| Jones Homes Limited | Real estate | 1970 |
| Jonnao Ltd | Financial services | 2024 |
| Jonnik Limited | Information & communication | 2006 |
| Josh Botham Tax & Accounting Services Limited | Professional & scientific | 2010 |
| Joshcameronconsulting Ltd | Professional & scientific | 2006 |
| Joshua a W Layton Ltd | Health & social care | 2026 |
| Joshua Management Group Limited | Administrative & support | 2003 |
| Jota Subsea Ltd | Information & communication | 2017 |
| Jote Holdings Ltd | Administrative & support | 2025 |
| Jovo Investments Limited | Financial services | 2015 |
| Jovoy Limited | Wholesale & retail | 2016 |
| Joyce Darfoor Ltd | Health & social care | 2009 |
| JP Construction (Sussex) Ltd | Construction | 2024 |
| JP Physio Limited | Other services | 2013 |
| JPB Futures Ltd | Financial services | 2017 |
| JPH Loft Conversions Ltd | Construction | 2021 |
| JPM Electrical Contractors Limited | Construction | 2008 |
| JPN Film Services Limited | Other services | 1974 |
| Jppatel Limited | Financial services | 2022 |
| Jpprojectsuk Ltd | Construction | 2025 |
| JPR Wood Ltd | Real estate | 2023 |
| Jprw Acquisitions Ltd | Real estate | 2018 |
| JPS CAD Services Limited | Professional & scientific | 2011 |
| JPS Renovation Ltd | Construction | 2018 |
| JPS Tiling Ltd | Construction | 2026 |
| JPU Ltd | Health & social care | 2019 |
| JR Sustainability Ltd | Professional & scientific | 2018 |
| Jrmack Limited | Financial services | 2022 |
| JS Health Consulting Ltd | Professional & scientific | 2024 |
| JS Home Improvements Ltd | Construction | 2021 |
| JS Just Smile Limited | Health & social care | 2022 |
| JS Projects Ltd | Professional & scientific | 1996 |
| JS Residences Ltd | Real estate | 2023 |
| JS Supreme Electricians Ltd | Construction | 2023 |
| Jsip Limited | Real estate | 2016 |
| JSS Plumbing and Heating (Southern) Ltd | Construction | 2018 |
| Jsystems Development Limited | Information & communication | 2006 |
| JT Plant Hire Limited | Administrative & support | 2020 |
| JT Reinstate Limited | Construction | 2019 |
| JTA Energy Consultants Limited | Administrative & support | 2009 |
| JTJ Investments Limited | Real estate | 2021 |
| JTP Accountants Ltd | Professional & scientific | 2026 |
| JTP Decorating Ltd | Construction | 2008 |
| JTS Civils Ltd | Administrative & support | 2012 |
| JTS Specialist Services Ltd | Administrative & support | 2011 |
| Judek Limited | Health & social care | 2023 |
| Judges Bakery Limited | Manufacturing | 2026 |
| Judytia Limited | Health & social care | 2016 |
| Juice Box Creative Limited | Information & communication | 2025 |
| Julia ELY Limited | Education | 2019 |
| Julie Silver Events Management Ltd | Administrative & support | 2016 |
| Juliettes Cakes Limited | Manufacturing | 2017 |
| Julo Ltd | Hospitality | 2018 |
| Jump Resources (U.K.) Ltd | Manufacturing | 2012 |
| Juniper Roofing Southern Limited | Construction | 2024 |
| Juniper VA Solutions Ltd | Administrative & support | 2023 |
| Jupiter OIL UK Ltd | Other services | 2024 |
| Just About Group Ltd | Wholesale & retail | 2020 |
| Just About Weddings Decor Ltd | Other services | 2023 |
| Just About Weddings Entertainment Ltd | Arts & recreation | 2023 |
| Just About Weddings Food and Drink Limited | Hospitality | 2024 |
| Just About Weddings Hair and Beauty Ltd | Other services | 2023 |
| Just About Weddings Ltd | Hospitality | 2026 |
| Just About Weddings Photo and Film Ltd | Information & communication | 2023 |
| Just About Weddings Planning Ltd | Wholesale & retail | 2023 |
| Just Another Artist Ltd | Professional & scientific | 2025 |
| Just Cat Flaps Ltd | Wholesale & retail | 2022 |
| Just Eros Limited | Wholesale & retail | 2011 |
| Just PDR Ltd | Wholesale & retail | 2017 |
| Just Print-It Ltd | Manufacturing | 2006 |
| Just Property Estate Agents (Fairlight) Limited | Real estate | 2008 |
| Just Shares Limited | Financial services | 1989 |
| Just Streets Ahead Limited | Real estate | 2016 |
| Justin Banks Limited | Wholesale & retail | 2013 |